SI1-1: The effect of early inlet valve closing on combustion within a direct injection spark ignition engine(SI: Spark-Ignition Engine Combustion,General Session Papers)

概要

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To develop an understanding of the combustion produced by two different valve strategies the techniques of combustion imaging, for flame front propagation, and laser Doppler anemometry, LDA, for the air flow and turbulence characteristics in the vicinity of the spark plug were applied in the optical engine configured to replicate the 2000 rpm 2.7 bar IMEP load point of a conventional thermodynamic engine for both valve strategies. A sequence of combustion images were taken at 4^0 CA intervals to span the entire combustion event with fifty images taken at each crankangle to produce a mean image for each crankangle in the sequence. A Matlab code, utilising the "jet" colormap, identified the minimum and maximum visible flame intensity levels and the intensity contour corresponding to the flame front overlaid with the combustion chamber outline. A radial coordinate system was applied which allowed the flame front propagation and velocity to be quantified in both the vertical and horizontal planes. Laser Doppler anemometry was applied to quantify the time resolved mean and fluctuating flow characteristics of the axial and cross flow components directly below the spark plug in the pent roof. The engine was motored, without fuel injection, to establish the flow field likely to exist at the time of spark and the appearance of the flame kernel.
2008-07-28